1. Field of the Invention
The present invention relates to a method for manufacturing a surface-emitting laser.
2. Description of the Related Art
Recently, attentions have been paid to a surface-emitting laser as a light source for optical communications or optical transmission or a light source of electronic photographs. The surface-emitting laser has such excellent properties that two-dimensional array is easily obtained and that it has a low threshold value and a single longitudinal mode. As such a surface-emitting laser, a photonic crystal surface-emitting laser has been developed which utilizes photonic crystals. Here, the photonic crystal is a structure having a refractive index periodicity equal to or smaller than that of light wavelength.
As for such a surface-emitting laser, a two-dimensional photonic crystal surface-emitting laser and its manufacturing method utilizing photonic crystals are disclosed in Japanese Patent Application Laid-Open No. 2000-332351 (Patent Document 1). The two-dimensional photonic crystal surface-emitting laser disclosed in Patent Document 1 has a photonic crystal periodic structure in which a refractive index periodicity is provided two-dimensionally in the vicinity of an active layer that emits light by carrier implantation, and is configured to cause resonance by the photonic crystal to generate surface emission.
More specifically, the surface-emitting laser of Patent Document 1 has, as illustrated in FIGS. 12A and 12B, a lower cladding layer 1212, an active layer 1216 and an upper cladding layer 1218 laminated on a substrate 1210. This lower cladding layer 1212 has a two-dimensional photonic crystal embedded in the vicinity of the active layer. On the upper cladding layer 1218, an upper electrode 1220 is arranged, while a lower electrode 1222 is arranged on the substrate 1210. When a voltage is applied to between the upper electrode 1220 and the lower electrode 1222 to inject carriers in the active layer 1216, the active layer emits light to cause laser oscillation by light resonance of the two-dimensional photonic crystal. In addition, Patent Document 1 also discloses the following manufacturing method of a semiconductor surface-emitting device applicable to the surface-emitting laser.
The manufacturing method of a semiconductor surface-emitting device has the following steps.
The steps are: a step of preparing a first piece having a first surface including a first substrate; a step of laminating a first conductive semiconductor layer, an active layer and a second conductive semiconductor layer sequentially on a main surface of a second substrate to form a second piece having a second surface along an extending direction of the main surface; a grating step of forming a two-dimensional diffraction grating in at least one of the first surface and the second surface; and a step of, after the grating step, bonding the first piece and the second piece in such a manner that the first surface and the second surface face each other.
Specifically, this manufacturing method of a semiconductor light-emitting device uses a method of directly bonding the semiconductor piece having a photonic crystal structure formed on its surface to another semiconductor piece via the surface having the photonic crystal structure formed thereon.
This method is said to be applicable to the surface-emitting laser because this enables manufacturing of a device having a photonic crystal structure inside the semiconductor.